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Title:Effect of sire line and rearing environment on the growth performance and carcass characteristics of growing-finishing pigs
Author(s):Grohmann, Nicholas
Advisor(s):Ellis, Michael
Department / Program:Animal Sciences
Discipline:Animal Sciences
Degree Granting Institution:University of Illinois at Urbana-Champaign
rearing environment
sire line
Gene–environment interactions (G × E interactions)
feeding level
Abstract:The effects of sire line and rearing environment on the growth performance and carcass characteristics of growing-finishing pigs were evaluated using 208 barrows from 2 purebred sire lines. The study was conducted as a randomized complete block design (blocking factor was the day of start of test) with a 2 x 5 factorial arrangement of the following treatments: Sire line (Green vs. Blue) and Rearing Environment [ (Penning/feeding regime) 1) Individual pen (Building 1)/Ad libitum, 2) Individual pen (Building 1)/Restricted, 3) Individual pen (Building 2)/Ad libitum, 4) Individual pen (Building 2)/Restricted, and 5) Standard group pen (Building 2)/Ad libitum]. Pen was the experimental unit. This study was carried out from an initial live weight of 38.4 ± 1.78 kg to two end points, namely to a fixed-weight of 122.5 kg mean pen live weight and to a fixed-time of 97 days on test (Week 14 of the study). For pigs on the restricted feeding treatment, the target restricted feeding level was 90% of the daily ad libitum feed intake of the standard group housed pigs (Trt. 5). The restricted feeding level was calculated within replicate. Throughout the study period the restricted fed pigs were fed twice per day at approximately 0700 and 1700 hours. Pigs were individually weighed at the start and end of the study period, and every two weeks until Week 12 of the study at which time they were weighed on a weekly basis until the end of the study. All feed additions and feed remaining in the feeder at the time of pig weighing were measured to determine feed intake and gain:feed ratio. At the end of Week 14, entire blocks were removed from test and transported to Cargill Meat Solutions (Beardstown, IL) for harvest. Pigs reared under restrict fed conditions had reduced average daily gain, daily feed intake and tenth rib backfat thickness as well as increased carcass lean content when compared to pigs reared under ad libitum fed conditions. The effect of restricted feeding on feed efficiency, however, was genotype dependent. For the Green sire line, there was no effect of feeding regime on feed efficiency; however, feed efficiency was greater under restricted compared to ad libitum feeding for the Blue sire line. Under ad libitum fed conditions, barrows housed in groups of 8 pigs (Trt. 5) had similar growth performance and carcass characteristics to barrows that were penned individually (Trt. 1 and 3). The presence of a treatment interaction in this study for feed efficiency, suggests that the two genotypes responded differently to changes in the environment, in this case feeding level, and highlights the importance that it is the combination of selection objectives and the environment in which pigs are tested in that create the differences between genotypes. Therefore, due to the unlimited combinations of genotypes and environments, the existence of G × E interactions should be evaluated independently for each combination of genotypes and environments.
Issue Date:2012-09-18
Rights Information:Copyright 2012 Nicholas Grohmann
Date Available in IDEALS:2012-09-18
Date Deposited:2012-08

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